The senses of taste and smell are at their heart recognition of volatile molecules. The sense of smell is designed to provide an animal with the ability to identify potentially helpful or harmful molecules. In animals, this sense occurs by the activation of thousands of individual chemical receptors, which give a qualitative and analog output. This qualitative information is of high enough quality to keep animals mostly healthy. Taste and smell phenomena may be used outside their normal relationship to food and health, for example in the use of bomb-sniffing dogs.
Man made scent-based detection methods may examine high volatility compounds by sampling air in an area of interest. For example, analogs of biological ‘smell’, such as a polymer-based biomimetic smelling (e.g. electronic noses developed by the company Cyrano), have been developed for qualitative analysis.
Another technique of molecular detection may use mass spectroscopy, which may identify molecules by their exact molecular weight. Unlike biomimetic smelling, mass spectroscopy may identify and quantify similar molecules in a complex mixture, such as by detailing the components of gasoline or the decomposition products from foodstuff.
In some types of gas analysis techniques, a canister may be placed under vacuum and sealed, then brought to an area for gas sampling. A valve on the canister may be opened slightly, and volatile gases from this area may be admitted to the canister. After a set time (which may be up to days), the canister valve may be closed, and the canister and its contents may be brought to a mass spectrometer for analysis.
In other techniques, a surface may be analyzed by mass spectroscopy by directly bombarding such a surface with laser energy while the surface is in a vacuum. Such techniques may identify molecules not generally considered as volatile. However, operation entirely in a vacuum may have drawbacks.